Use of a pentagonally-shaped alumina support coated with palladium in the preparation of tertiary butyl alcohol from tertiary butyl hydroperoxide

Abstract: A method for preparing tertiary butyl alcohol wherein a feedstock comprising a solvent solution of tertiary butyl hydroperoxide in tertiary butyl alcohol or a mixture of tertiary butyl alcohol with isobutane is charged to a hydroperoxide decomposition reaction zone containing a catalytically effective amount of a hydroperoxide decomposition catalyst consisting essentially of pentagonally cross-sectioned alumina having palladium deposited thereon and is brought into contact with the catalyst in liquid phase with agitation under hydroperoxide decomposition reaction conditions to convert the tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol.

Description: This invention relates to the catalytic decomposition of tertiary butyl hydroperoxide (TBHP). More particularly, this invention relates to a method for the preparation of tertiary butyl alcohol (TBA) by the catalytic decomposition of tertiary butyl hydroperoxide. Still more particularly, this invention relates to a method wherein a pentagonally-shaped alumina support coated with palladium is used to catalyze the substantially selective decomposition of tertiary butyl hydroperoxide to tertiary butyl alcohol. It is known to react isobutane with oxygen, either thermally or catalytically, to form a peroxidation reaction product wherein the principal peroxide that is formed is tertiary butyl hydroperoxide. It is also known to thermally or catalytically decompose the tertiary butyl hydroperoxide to form tertiary butyl alcohol. In the text entitled "Organic Peroxides" edited by Daniel Swern (Wiley Interscience, a Division of John Wiley & Sons, New York), in Vol. II on page 157 it is stated that the metal-ion-catalyzed decomposition of primary hydroperoxides yields mainly alcohols, aldehydes and carboxylic acids, citing as an example the decomposition of hydroxymethyl hydroperoxide with aqueous ferrous sulfate to provide formaldehyde, formic acid and water. Sanderson et al. disclose the use of a variety of catalysts for the decomposition of tertiary butyl hydroperoxide in a series of U. S. patents, including a catalyst composed of unsupported nickel, copper, chromia and iron (U. S. Patent No. 4,704,482), a catalyst composed of iron, copper, chromia and cobalt (U. S. Patent No. 4,705,903), a catalyst composed of a base treated hydrogenation catalyst from groups VIA or VIII of the Periodic Table (U. S. Patent No. 4,742,179), a catalyst consisting essentially of nickel, copper, chromium and barium (U. S. Patent No. 4,873,380), a catalyst composed of a metal phthalocyanine promoted with a rhenium compound (U. S. Patent No. 4,910,349), a catalyst composed of a base promoted metal phthalocyanine compound (U. S. Patent No. 4,912,269), a catalyst composed of a soluble ruthenium compound promoted with a bidentate ligand (U. S. Patent No. 4,912,033), a catalyst composed of a metal porphine such as iron (III) or manganese (III) promoted with an alkyl thiol or an amine, a catalyst composed of an imidazole promoted metal phthalocyanine compound (U. S. Patent No. 4,912,266), (U. S. Patent No. 4,922,034), a catalyst composed of a metal phthalocyanine promoted with a thiol and a free radical inhibitor (U. S. Patent No. 4,922,035), a catalyst composed of a borate promoted metal phthalocyanine (U. S. Patent No. 4,922,036), or a catalyst composed of a soluble ruthenium compound and an iron compound such as an acetate, a borate, a bromide, a chloride, a 1,3-propanedionate, a 2-ethyl-hexanoate, an iodide, a nitrate, a 2,4-pentanedionate, a perchlorate or a sulfate (U. S. Patent No. 5,025,113). As stated, when isobutane is reacted with molecular oxygen, the principal products of the reaction are tertiary butyl alcohol and tertiary butyl hydroperoxide. However, minor amounts of other contaminants are also formed. A minor amount of water will be formed, which will normally amount to 0.5 to 1 wt.% of the reactor effluent. The amount of byproduct water that is produced is a function of the severity of the reaction conditions employed and will tend to increase as the severity of the reaction conditions is increased. As indicated, tertiary butyl hydroperoxide is useful as a raw material for the manufacture of tertiary butyl alcohol. The tertiary butyl alcohol can be formed by catalytic decomposition of the tertiary butyl hydroperoxide. In accordance with the present invention, a solvent solution of a tertiary butyl hydroperoxide charge stock is brought into contact with a catalytically effective amount of a hydroperoxide decomposition catalyst in a hydroperoxide decomposition reaction zone in liquid phase, preferably with agitation, to convert the tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol, the hydroperoxide decomposition catalyst being a supported hydroperoxide decomposition catalyst consisting of pentagonally cross-sectioned pellets of alumina having deposited thereon from 0.1 to 5 wt.%, preferably 0.1 to 1 wt.%, of palladium and tertiary butyl alcohol is recovered from the products of the hydroperoxide decomposition reaction. The tertiary butyl alcohol will not be the only decomposition product that is formed. Minor amounts of other oxygen-containing materials will also be formed. The tertiary butyl alcohol that is recovered from the decomposition reaction mixture will be contaminated with the oxygenated impurities. The starting materials for the process of the present invention are a tertiary butyl hydroperoxide feedstock and a pentagonally-shaped alumina support coated with palladium. The Tertiary Butyl Hydroperoxide Feedstock The tertiary butyl hydroperoxide charge stock may comprise an isobutane oxidation product wherein the tertiary butyl hydroperoxide is dissolved in a mixture of isobutane and tertiary butyl alcohol or may comprise an isobutane oxidation product enriched by the addition of tertiary butyl alcohol, such that the solution of tertiary butyl alcohol in the mixture of isobutane with tertiary butyl alcohol contains from 5 to 30 wt.% of tertiary butyl hydroperoxide. Alternatively, the isobutane reaction product may be charged to a distillation zone where unreacted isobutane is removed as a distillate fraction for recycle to thereby provide a solution of tertiary butyl hydroperoxide in tertiary butyl alcohol containing 5 to 30 wt.% of tertiary butyl hydroperoxide. The Catalyst System The hydroperoxide decomposition catalyst to be used in accordance with the present invention consists of pentagonally cross-sectioned pellets of alumina having deposited thereon from 0.1 to 5 wt.% of palladium. Catalytic Decomposition of Tertiary Butyl Hydroperoxide The process of the present invention may be conducted continuously by passing the reactants through a tubular reactor. The catalytic decomposition of the tertiary butyl hydroperoxide is preferably conducted at a temperature within the range of 20° to 250°C, preferably 60° to 120°C, and more preferably at a temperature within the range of 80° to 100°C. The reaction is preferably conducted at a pressure sufficient to keep the reactants and the reaction products in liquid phase. A pressure of 0.1 to 69 MPa (0 to 10,000 psig), preferably 0.1 to 7 MPa (0 to 1000 psig) may be used, if desired. As described hereafter, the rates of the charge solution to the reaction zone should be adjusted in order to provide an appropriate contact time within the reactor. In accordance with a preferred embodiment of the present invention, isobutane is reacted with oxygen in an oxidation zone under oxidation reaction conditions including a temperature of 135 to 155°C., a pressure of 2.1 to 5.6 MPa (300 to 800 psig), and a holding time of 2 to 6 hours to provide an initial oxidation reaction product comprising unreacted isobutane, tertiary butyl hydroperoxide, tertiary butyl alcohol, and oxygen-containing by-products. The initial oxidation reaction product is then used as the tertiary butyl hydroperoxide charge stock of the present invention. If the concentration of tertiary butyl hydroperoxide in the tertiary butyl hydroperoxide charge stock is more than 30 wt.% of the initial oxidation reaction product, the initial oxidation reaction product can be diluted with an amount of tertiary butyl alcohol sufficient to lower the concentration of the tertiary butyl hydroperoxide to a desired percentage, to provide, for example, a tertiary butyl hydroperoxide charge stock containing from 15 to 25 wt.% of tertiary butyl hydroperoxide. Alternatively, the initial oxidation reaction product may be fractionated in any appropriate manner (e.g., by distillation in a distillation zone) to remove the isobutane therefrom for recycle and to provide a solution of tertiary butyl hydroperoxide and tertiary butyl alcohol which will normally contain from 5 to 30 wt.% of tertiary butyl hydroperoxide. The solution of tertiary butyl hydroperoxide in tertiary butyl alcohol is then charged to a catalytic hydroperoxide decomposition zone where it is brought into contact with a catalyst of the present invention to substantially selectively convert the tertiary butyl hydroperoxide to tertiary butyl alcohol with high yields and selectivities. The process of the present invention may be practiced in a continuous manner by continuously charging the tertiary butyl hydroperoxide charge stock to a reactor containing a fixed bed of pelleted hydroperoxide decomposition catalyst, at a space velocity that is suitably in the range of 0.5 to about 3 volumes of tertiary butyl hydroperoxide charge stock per volume of catalyst per hour. Preferably, the space velocity is within the range of 1 to 2 volumes of tertiary butyl hydroperoxide charge stock per volume of catalyst per hour. The reaction product from the tertiary butyl hydroperoxide decomposition step may then be fractionated in any suitable manner, such as by distillation to recover the tertiary butyl alcohol. The invention will be further illustrated by the following non-limiting examples. EXAMPLES Reactor The reactor was a stainless steel tube (13mm x 736mm) which was electrically heated. Liquid feed was pumped into the bottom of the reactor. Pressure regulation was with a Skinner Uni-Flow® valve and a Foxboro® controller. The liquid feed was pumped with a Ruska® dual drive pump. Feed 20% TBHP was prepared from 55% isobutane peroxidation reactor effluent by diluting with commercial TBA. Catalyst A 200 cc sample of 1% palladium supported on pentagonally cross-sectioned alumina pellets, where the palladium has been coated onto the exterior surface of the alumina to an average thickness of 200 microns. The average diameter of the pellets was 2 mm. The pellets were placed in a reactor and heated to 140°C for 4.0 hours in a stream of hydrogen. The sample was cooled under hydrogen and stored under a nitrogen atmosphere. Analytical Analysis of the reactor effluent was by Gas Chromatography. Details are given in the following tables. CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 1 2 3 4 Catalyst 1% Pd on Al 2 O 3 pellets (pentagonal cross-section) Catalyst (cc) 100 100 100 100 Pressure (MPa) 2.1 2.1 2.1 2.1 Feed Rate (cc/Hr.) 50 50 50 50 Temperature (°C) 60 80 100 120 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 0.5 0.5 0.5 0.5 TBHP Conversion (mol.%) 75.8 97.4 100.0 100.0 Selectivity IC4= (mol.%) 0.0 0.0 0.0 0.4 Sel. Acetone (mol.%) 6.4 14.3 21.3 23.1 Sel. Methanol (mol.%) 1.1 3.4 2.6 5.4 Sel. TBA (mol.%) 84.1 81.3 76.0 75.3 Sel. DTBP (mol.%) 9.5 4.5 2.7 1.6 Composition IC4= 0.000 0.000 0.000 0.002 0.050 MEOH/MF 0.005 0.065 0.248 0.192 0.399 Acetone 0.013 0.650 1.852 2.834 3.067 TBA 78.494 91.456 95.420 95.254 95.261 DTBP 0.049 1.251 0.770 0.490 0.309 TBHP 20.512 4.969 0.539 0.002 0.003 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 5 6 7 Catalyst 1% Pd on Al 2 O 3 pellets (pentagonal cross-section) Catalyst (cc) 100 100 100 Pressure (MPa) 2.1 2.1 2.1 Feed Rate (cc/Hr.) 100 100 100 Temperature (°C) 60 100 120 Time on Stream (Hr) 4 4 4 Space Vel. (cc/cc) 1.0 1.0 TBHP Conversion (mol.%) 57.1 84.7 100.0 Selectivity IC4= (mol.%) 0.0 0.0 0.4 Sel. Acetone (mol.%) 6.1 11.3 24.4 Sel. Methanol (mol.%) 1.2 3.1 4.1 Sel. TBA (mol.%) 84.6 83.6 74.3 Sel. DTBP (mol.%) 9.3 5.1 1.3 Composition IC4= 0.000 0.000 0.000 0.051 MEOH/MF 0.005 0.057 0.198 0.305 Acetone 0.013 0.472 1.283 3.237 TBA 78.494 88.259 92.557 95.262 DTBP 0.049 0.936 0.765 0.269 TBHP 20.512 8.790 3.133 0.003 CATALYTIC CONVERSION OF TERT-BUTYLHYDROPEROXIDE TO TERT-BUTYLALCOHOL RUN A 8 9 10 11 Catalyst 1% Pd on Al 2 O 3 pellets (pentagonal cross-section) Catalyst (cc) 100 100 100 100 Pressure (MPa) 2.1 2.1 2.1 2.1 Feed Rate (cc/Hr.) 200 200 200 200 Temperature (°C) 60 80 100 120 Time on Stream (Hr) 4 4 4 4 Space Vel. (cc/cc) 2.0 2.0 2.0 2.0 TBHP Conversion (mol.%) 34.2 71.0 93.9 100.0 Selectivity IC4= (mol.%) 0.0 0.0 0.0 0.3 Sel. Acetone (mol.%) 5.8 9.9 16.1 25.1 Sel. Methanol (mol.%) 1.4 2.6 5.7 4.1 Sel. TBA (mol.%) 85.4 84.5 80.8 73.6 Sel. DTBP (mol.%) 8.8 5.6 3.2 1.3 Composition IC4= 0.000 0.000 0.000 0.000 0.043 MEOH/MF 0.005 0.040 0.142 0.396 0.306 Acetone 0.013 0.273 0.944 2.009 3.327 TBA 78.494 84.360 90.336 93.977 95.231 DTBP 0.049 0.550 0.712 0.541 0.260 TBHP 20.512 13.505 5.947 1.246 0.010 A novel commercial catalyst (1% palladium on star-shaped alumina support) was very active for the conversion of TBHP. Selectivity to TBA was good. For example, at 80°C and a space velocity of 0.5, this catalyst gave 97.4% TBHP conversion and a selectivity to TBA of 81.3%, acetone of 14.3%, methanol of 3.4% and DTBP of 4.5%. "Typical" peroxide conversion catalysts under these conditions usually give 80% or less conversion.

Claims: A method for the decomposition of tertiary butyl hydroperoxide to tertiary butyl alcohol, wherein a solvent solution of a tertiary butyl hydroperoxide charge stock is brought into contact with a hydroperoxide decomposition catalyst, characterized in that said hydroperoxide decomposition catalyst comprises pentagonally cross-sectioned pellets of alumina having palladium deposited thereon. A method as claimed in claim 1 wherein the solvent comprises tertiary butyl alcohol, or a mixture thereof with isobutane. A method as claimed in Claim 1 or Claim 2, wherein a solution of a tertiary butyl hydroperoxide charge stock that contains from 5 to 30 wt.% of tertiary butyl hydroperoxide is brought into contact with a catalytically effective amount of a hydroperoxide decomposition catalyst in a hydroperoxide decomposition reaction zone in liquid phase with agitation under hydroperoxide conversion conditions including a temperature within the range of 20° to 250°C. and a pressure of 0.1 to 7 MPa (0 to 1,000 psig) to convert said tertiary butyl hydroperoxide to decomposition products, principally tertiary butyl alcohol, characterized in that said hydroperoxide decomposition catalyst consists of pentagonally cross-sectioned pellets of alumina having deposited thereon from 0.1 to 5 wt.% of palladium. A method as claimed in anyone of Claims 1 to 3, wherein the temperature is in the range of 40° to 150°C. and the pressure is 0.1 MPa.

Inventors: KNIFTON JOHN FREDERICK, SANDERSON JOHN RONALD, KNIFTON, JOHN FREDERICK, SANDERSON, JOHN RONALD
Applicants: HUNTSMAN SPEC CHEM CORP, HUNTSMAN SPECIALTY CHEMICALS CORPORATION
Application year: 1994
Main classification: C07C29
IPC codes: C07B61, B01J23, C07C409, C07C27, B01J35, C07C31, C07C29, B01J21